Résumé
Homogeneous and heterogeneous catalysts have, each, specific advantages. While homogeneous catalysts are typically associated with efficient chemical transformations at low temperatures (high selectivity) and molecular understanding of catalytic events (structure – activity relationship), heterogeneous systems are typically preferred in term of processes (easier regeneration and separation processes). Here, we will show how it is possible to combine the advantages of homogeneous and heterogeneous catalysts by the controlled functionalization of the surfaces of oxide materials and by the characterization of surface species at the molecular level, thus allowing more predictive approaches.
We will illustrate the power of this approach with the development of well-defined "single-sites", whose performance and stability can in some cases exceed these of both homogeneous and heterogeneous catalysts.
With our current level of understanding of surfaces, we will also discuss new directions in this field, i.e. understanding defect sites of surfaces and metal-support interactions at the molecular level, introducing diversity in oxide chemistry, controlling the growth of nanoparticles, the development of NMR techniques for the expeditious characterization of surface species in order to bridge the gap between well-defined systems and industrial catalysts.
